Swimming accessory



Feb. 26, 1963 w. K. CROWDER 3, 8

SWIMMING ACCESSORY Filed May 11, 1959 3,078,482 SWIRIMHNG ACQESSGRY WyiyK. Crowder, 6405 Livernois N., Troy, Mich. Filed May 11, 1959, Ser. No.812,214 4 Qiaims. (Cl. 9-60?) The present invention relates to animproved swimming accessory for attachment to the legs of a swimmer toachieve improved utilization of leg muscles in propulsion of a swimmerthrough the Water.

One important object of the present invention is to provide an improvedpropulsion device for attachment to a swimmers legs.

Other objects of the invention are: to provide an improved device ofthis character whereby normal flexing of the swim-mers leg as in walkingis translated into an effective forward propulsion in a directiongenerally longitudinally along the swimmers body; to provide apropulsion device of this character which is effective to produce aforward propulsion force on each stroke of the 'swimmers leg with arelatively high degree of efliciency; to provide an improved device ofthis character which is constructed in the form of a variable hydrofoilhaving an automatically reversible camber so that it is equal- 1yeffective on both the up and the down leg strokes; to provide animproved swimming propulsion device for attachment to a swimmers legwhich is efiective to create a relatively strong forward propulsiveforce in response to relatively easy flexing motion of the leg in a'vertical direction; and in general to provide an improved device of thischaracter which is relatively simple and inexpensive in construction,and which is easy and comfortable to use, permitting the swimmer topropel himself with an easy, natural leg motion.

The foregoing and other objects and advantages of the invention willbecome apparent from the following detailed description of a preferredembodiment thereof, taken in conjunction with the drawing, wherein:

FIGURE 1 is a side elevational view of a swimmer equipped withpropulsion devices according to the invention;

FIGURE 2 is a plan view of the swimmer shown in FIGURE 1;

FIGURE 3 is a sectional view of one of the propulsion devices accordingto the invention, the view being taken along the line 3-3 of FIGURE 2;

FIGURE 4 is a horizontal sectional view of the device shown in FIGURE 3;and,

FIGURE 5 is an enlarged view of the portion of FIG- URE 4 within thecircle 4 thereof.

The muscles in the human leg are naturally highly developed for walkingand running. They also adapt readily to bicycle riding. Bicycle ridersuse hip, knee and ankle muscles much in the same manner as they are usedin walking or running. In swimming, however, the general instruction isto stiffen the knees and kick from the hips. Even with the popularwebbed foot attachment, the same instruction still applies. Aconsiderable amount of effort is required to keep the swim mers legsrelatively stiff, effort which does not do any work and does not producea forward thrust. The propulsion device of the present invention permitsa swimmer to avoid the strain of keeping his legs stiff, and permits himto use his already developed walking and running muscles in theirnatural action to produce a forward propulsion force.

Broadly, the device of the present invention consists of a flexiblehydrofoil mounted for limited angular oscillation on a supportingstructure which may be strapped to the swimmers leg. The hydro-foil isspring urged toward a neutral position and is rotatably deflectableagainst the urging of the spring away from its neutral position ineither direction, depending upon the direction of the leg movement. Inits unstressed condition, the hydrofoil has no camber, but it flexes inresponse to water resistance to a cambered shape, with the camber in onedirection during the upstroke of the leg, and in the opposite directionduring the downstroke. This camher action is an important feature of thepresent invention since it achieves smooth acceleration of the water inthe rearward direction as the water passes along the hydrofoil.

Referring now to the drawing, a set of propulsion devices 10, 12, and 14are illustrated therein attached to the legs 16 and 18 of a swimmer. Thedevices 10, 12, and 14 are essentially similar to each other except fordifferences in size. Preferably, the devices and 12, which are attachedto the swimmers thighs just above the knee, are relatively large sincethe muscles which operate the thigh are relatively large and strong. Thedevices It? on the outer sides of the legs may be relatively long, andto allow adequate clearance, the devices 12 mounted on the inner sidesof the legs are relatively short. The devices 14 which are attached atthe ankles may be smaller than the thigh-attached devices 10 and 12 inview of the difference in muscle strength for driving them. Since thedevices 10, 12, and 14 are all exactly similar to each other, except fordifferences in size, their construction and operation may be fullyappreciated by a consideration of the device 14 which is shown in detail7 in FIGS. 3, 4, and 5.

The propulsion device 14 includes a hydrofoil 20, which is made of aresiliently yieldable material such as molded rubber, and is formed in ashape generally similar to that of an airplane wing of symmetrical crosssection.

When the hydrofoil 20 is in its normal, unstressed condition, its upperand lower surfaces 28 and 30 are symmetrically disposed relative to eachother on opposite sides of a median plane, and the hydrofoil has nocamber. The hydrofoil 20 is mounted so that it flexes autoy matically toa cambered form during use, as shown in FIG. 3. The hydrofoil 20 isfixed to a camber pitch tube 32, which extends longitudinally throughthe hydrofoil near its leading edge 24, and forward of its longitudinalcenter line. The camber pitch tube 32 is rotatable on a main pitch tube34, which extends coaxially within the r camber pitch tube and isrigidly secured as by welding to outer and inner plates or shields 36and 37, respectively. The outer shield 36 is rigidly secured to theouter end of an elongated torsion spring 38, which extends coaxiallywithin the main pitch tube 34, and which is anchored at its inner endupon the support bracket 40. In this manner the wing 20 is mounted forlimited angular oscillation about the axis of the torsion spring 38. Thesupport bracket 40 may be of any desired shape to conform to theswimmers leg and may be attached thereto by an convenient means such asthe straps 42, illustrated. A support tube 44 is also rigidly secured tothe mount 40 and extends within the main pitch tube 34 and around thetorsion spring 38 to maintain the torsion spring in proper alignment andsupport it against lateral deflection. A camber pitch bar 48 extendsbetween the inner and outer shields 36 and 37, respectively, passingthrough the hydrofoil 2% near the trailing edge 26 thereof. The bar 48is a slip fit within the hydrofoil 20.

In operation, the angle of incidence of the hydrofoil 2t! is determinedby the resilience of the torsion spring 38 and the velocity anddirection of the device through the water. The axis of support isforward of the center line of the hydrofoil 2% so that the hydrofoiltilts responsively to the force exerted upon its upper and lowersurfaces 28 and 30, respectively, producing an inclined plane effect toconvert the vertical leg movement into a forward thrust.

Patented Feb. 26, 1963 ported forward of its center line upon the mainpitch tube/3'4 and aft of its center line upon the pitch bar 48; Thisconstruction permits the hydrofoil 20 to flex in the manner illustratedin FIGURE 3 in response to.

loading, in either direction. The camber action contributes to theefficiency of the hydrofoil 20', causing the water to be uniformlyaccelerated rearwardly as it passes across the hydrofoil from theleading edge 24 toward the trailing edge 26, so that the entire surfacearea of the hydrofoil 20 is effective to develop forward thrust. Thecamber action, and the streamlined shape of the hydrofoil 20 minimizedrag. The device is thus efiective" to assist the swimmer to gainmaximum forward thrust'with' a minimum expenditure of effort.

In use, the devices 10, 12, and 14 are secured to the swimmerslegs, andthe swimmer uses a natural leg'motion, permitting his legs to flexmoderately as in walking. Excessive flexing is not desirable because ofdrag due to-the" legs themselves. As the legs move up and down',-.thehydrofoils tilt back and forth to adjust their angles-of incidence inaccordance with the direction of leg motion, and also flex ashercinabove described inmeans supporting said hydrofoil for flexing intoan arcu-' ateiiform. concave in the instantaneous direction of thedriving motion.

2. A water propulsion device adapted to be worn byaswimmer comprising aflexible wing-like member, means. for mounting saidmember foroscillation about an axisgenerally parallel to and forward of a linemid- Wayibetween the leading and trailing edges of saidmemberand'constitutingthe soleconnection of said member tousaid swimmer,and means for restricting flexing of the trailing edge of said memberrelative to said means,

wherebyv surface loading of said member causes it tofi'ex into arcuateform concave toward the loading force.

3. A swimming accessory for attachment to a swimmers leg to produce aforward thrust in response to flexing of the leg comprising a flexiblehydrofoil, and means for attaching said hydrofoil to a swimmers leg,said attaching means including a pivot for pivotally mounting saidhydrofoil, means for fixing said pivot upon the swimmers leg in aposition projecting laterally therefrom, a spring for resiliently urgingsaid hydrofoil about said pivot toward a predetermined angular positionrelative to the swimmers leg, and rigid means connecting portions ofsaid hydrofoil adjacent the leading and trailing edges thereof so thatsaid hydrofoil flexes in response to surface loading into arcuate formconcave toward the loading force.

4. A swimming accessory for attachment to a swimmers leg to produce aforward thrust in response to flexing of the leg comprising a flexiblehydrofoil, and mounting means for mounting said hydrofoil upon aswimmers leg, said mounting means including an elongated torsion spring,attaching means for attaching said spring at one end thereof in fixedposition upon a swimmers leg and projecting therefrom, a pivot fixed tothe end of said spring opposite from said one end and extending throughsaid hydrofoil, a pair of rigid shields mounted at opposite ends of saidpivot and fixed relativethereto, means journaling said hydrofoil uponsaid pivot between said shields along a line forward of the center lineof said: hydrofoil, and means connecting said shields to said hydrofoiladjacent to the trailing edge of said hydro foil, whereby theyieldability of said torsion spring permits tilting of said hydrofoil inadirection to rovide a forward thrust in response to a transverse legmotion and said'hydrofoil is caused by the water resistance to flex intoarcuate' form concave in the direction of the leg motion thereby toaccelerate the water rearwardlyi asitpasses over thevworking surface ofthe hydrofoil.

References @i'ted in the file off this patent UNITED' STATES PATENTS

1. A WATER PROPULSION DEVICE FOR TRANSLATING AN OSCILLATING DRIVINGMOTION INTO A THRUST IN A DIRECTION GENERALLY TRANSVERSE TO THE DRIVINGMOTION COMPRISING A FLEXIBLE HYDROFOIL, MEANS FOR MOUNTING SAIDHYDROFOIL FOR LIMITED ANGULAR OSCILLATION ABOUT AN AXIS GENERALLYPERPENDICULAR TO BOTH THE DESIRED DIRECTION OF THRUST AND TO THEDIRECTION OF THE OSCILLATING DRIVING MOTION, AND MEANS SUPPORTING SAIDHYDROFOIL FOR FLEXING INTO AN ARCUATE FORM CONCAVE IN THE INSTANTANEOUSDIRECTION OF THE DRIVING MOTION.